worf928

I'm in the process of fixing 928 "Battery Death Syndrome" (BDS) on an '87. I have isolated all static current draw and find that the Alarm ECU is eating ~73 mA.

Is this normal? Does anyone know the minimum current draw of the Alarm ECU?

NOTE: Nothing in the car is connected to the battery except the 4 wires that bypass the front main engine (FME) harness. I've isolated all potential culprits that draw from those and the alarm ECU is the culprit.

1) The FME is disconnected at the jump post.
2) The ABS power is disconnected from the FME.

I have verified that when the Alarm ECU is unplugged the current draw goes to zero. So, with everything else disconnected I'm pretty sure it has to be the Alarm ECU drawing the ~73mA.

Normal?
or
Abbynormal?

worf928

FYI, in addition to the Alarm ECU's draw, I find:
The LH draws 1 mA.
The EZK draws 3 mA.
Something else on the fuse panel-side of the front main harness eats 3 mA. (Interior light fuse is out. Maybe the door pins. I dunno. I'm not worried about 3 mA. So, with the interior light's fuse pulled and with the alarm ECU out, I'd have a static draw of about 7 mA. Which would be the schizzle....)

Alan

Dave - The alarm should be of the order of 10mA or less (more likely 5mA) when inactive. Your value is definitely a problem.

Alan

worf928

My thought as well. This alarm ECU has had to deal with shorted door pins, shorted lock contact switches, etc. So, I'd not be surprised if it decided to pack-up its marbles and go home. But, even with all that history (and new pins and contact switches) the alarm still seems to work as designed.

The key question here is 'inactive'. My assumption is that with the FME disconnected and only the 'extra' wires from the battery still connected to the car that this should simulate 'inactive.' A further assumption is that there's nothing else - undocumented - branching off the FME between the battery and the jump post since the main positive cable is still attached.

At this point the pod and center console are out. The right door harness is disconnected. So, I cannot do the 'classical' test of locking all the doors and watching the draw in a normal fashion.

Crap... I just realized that the contact switches, pins, and/or hood switch may be powered via the the Alarm ECU. But the switches are momentary contact. Nevertheless.... Need to check that in the diagrams... and they are not handy now. That'll need to wait until tomorrow.

Alan

Dave - take the unit out and test it on its own power to 30 terminal and Ground to 31 - what supply current then...?

HN, A, E, 15, 87a & MK can all float - set 61 to Ground and see if it makes any difference.

- Test that 15 & 87a are connected together with an ohmmeter/DMM (powered or not)
- Test that HN has very high impedance >>10Mohms to 30

Alan

worf928

In other words, unplug the OTHER plug on the Alarm ECU.

Thanks Alan.

RKD in OKC

My glove box latch was loose on my 90GT. It held the door closed, but not tight enough to turn off the light. Would run the battery down over night. It started at the exact same time I upgraded the stereo. It was very frustrating as I assumed it had to do with the new stereo wiring.

Jim bailey - 928 International

Yes the old question , Is the glove box light on if no one sees it ? The red door warning lights also trip people up when searching for a draw.."But I turned off all the interior lights. "

worf928

OK. False Alarm. No pun intended. Nothin' to see here. Move along....

Door pin: 30mA
Hood switch: 30mA
Hatch switch: 8mA
Alarm ECU: 5mA
-> 73mA